1. Field of the Disclosure
Embodiments of the disclosure relate to small antenna apparatuses suitable for polarization diversity antennas and multiple antennas for MIMO transmission, for example.
2. Description of the Related Art
A widely known example of such small antenna apparatuses has a configuration in which two chip antennas having an electric length of about ¼ of the wavelength λ of the frequency band used are arranged side by side on a dielectric substrate. However, in the antenna apparatus having such a configuration, if the distance between the chip antennas is not set to about λ/2, the two chip antennas interfere with each other, and hence predetermined antenna characteristics are not obtained. Consequently, when the 2.4 GHz frequency band is used, the two chip antennas need to be spaced apart from each other by about 6 cm, making the antenna apparatus unsuitable as an antenna apparatus which needs to be of reduced size.
Hence, to date, as described in Japanese Unexamined Patent Application Publication No. 2002-280828, for example, an antenna apparatus has been proposed which has a configuration in which two L-shaped pattern antennas made of metal conductor meandering lines are arranged side by side on the surface of a dielectric substrate, and each of the pattern antennas is made to operate as a center-feed dipole antenna having an electric length of about λ/2. In the proposed existing apparatus, the two pattern antennas are patterned so as to be L-shaped along one corner and the other corner of a side edge of the dielectric substrate, and the respective ends of the L-shaped antennas face each other with a relatively small gap therebetween. Since the antennas are arranged in such a manner that the polarization plane of the radiation electric field of one pattern antenna is orthogonal to the polarization plane of the radiation electric field of the other pattern antenna, the two antennas are highly isolated from each other and provide favorable antenna characteristics. Hence, the antenna apparatus which is favorable as, for example, a polarization diversity antenna can be easily reduced in size. Note that the meandering line is a known technology to obtain an increased electric length for a pattern antenna.
In the existing example disclosed in Japanese Unexamined Patent Application Publication No. 2002-280828, since the two L-shaped pattern antennas with the ends of the L shapes thereof facing each other are fed at the respective center portions, the distance between the feeding points of the pattern antennas unavoidably becomes large. Hence, in such an existing example, long and complex wiring patterns need to be formed to connect the feeding points of the pattern antennas to a high frequency circuit, thereby prohibiting decreased cost and freedom of design.
These and other drawbacks exist.